in.vtf 


Issued  April  30 


U.  S.  DEPARTMENT  OF   AGRICULTURE, 

I'.l  REATJ  OF  PLANT  I  NDl'STKY-- Cinular  No.  4. 
1(.   r.  GALl  0\\  IlV,  Chief  of  Bureau. 


THE  TREATMENT  OF  DAMPING-OFF 
IX  CONIFEROUS  SEEDLINGS. 


PERLEY    SPAULDING, 

Scientific  Assistant,   Laboratori    <>f  Foresi    Pathology. 


38045     rir.  4— 08 


WASHINGTON  ;  GOVERNMENT  MINTING  OFFICE  :  190« 


BUREAU  OF  PLANT  INDUSTRY. 

Pathologist  and  Physiologist,  and  chief  <if  Bureau,  Beverly  T.  Galloway. 

Pathologist  and  Physiologist,  and  Assistant  Chief  of  Hun  ait,  Albert  F.  Woods. 

Laboratory  of  Plant  Pathology,  Erwin  F.  Smith,  Pathologist  in  Charge. 

Investigations  of  Diseases  of  Fruits,  Merton  B.  Waite,  Pathologist  in  Charge. 

Laboratory  of  Forest  Pathology,  Haven  Metcalf,  Pathologist  in  Charge. 

Truck  Crop  Diseases  and  Plant  Disease  Survey,  William  A.  Orton,  Pathologist  in  Charge. 

Plant  Life  History  Investigations,  Walter  T.  Swingle,  Physiologist  in  Charge. 

Cotton  Breeding  Investigations,  Archibald  D.  Shame]  and  Daniel  N.  Shoemaker,  Physiolo- 
gists in  Charge. 

Tobacco  Investigations,  Archibald  I).  Sbamel,  Wightman  W.  Garner,  and  Ernest  H. 
Mathewson,  in   Charge 

Coin   Investigations,  Charles  P.   Hartley.   Physiologist   in  Charge. 

Alkali  and  Drought  Resistant  Plant  Breeding  Investigations,  Thomas  II.  Kearney,  Physi- 
ologist in  Charge. 

Soil  Bacteriology  and  Water  Purification  Investigations,  Karl  F.  Kellerman,  Physiologist 
in  Charge. 

Bionomic  Investigations  of  Tropical  and  Subtropical  Plants,  Orator  F.  Cook,  Bionomist 
in  Charge. 

Drug  and  Poisonous  Plant  Investigations  and  Tea  Culture  Investigations,  Rodney  H. 
True,  Physiologist  in  Charge. 

Physical  Laboratory,  Lyman  J.  Briggs,  Physicist  in  Charge. 

Crop  Technology  and  Fiber  Plant  Investigations,  Nathan  A.  Cobb,  Crop  Technologist  in 
Charge. 

Taxonomic  and  Range  Investigation*,  Frederick  V.  Coville,  Botanist  in  Charge 

Farm   Management  Investigations,  William  ,T.  Spillman,  Agriculturist  in  Charge. 

Grain   Investigations,  Mark  Alfred  Carleton,  Cerealist  in  Charge. 

Arlington  Experimental  Farm,  Lee  ('.  Corbett,  Horticulturist  in  Charge. 

I  egetable  Testing  Guldens,  William  W.  Tracy,  sr.,  Superintendent. 

Sugar-Beet  Investigations,  Charles  O.  Townsend,  Pathologist  in  Charge. 

Western  Agricultural  Extension  Investigations,  Carl  S.  Scofield,  Agriculturist  in  Charge. 

Dry-Land  Agriculture  Investigations,  B.  Channing  Chilcott,  Agriculturist  in  Charge. 

Pomological  Collections,  Gustavus  B.  Braekett,  Pomologist  in  Charge. 

Field  Investigations  in  Pomology,  William  A.  Taylor  and  (J.  Harold  Powell,  Pomologists 
in  Charge. 

Experimental  Gardens  ami  Grounds,  Edward  M.  Byrnes,  Superintendent. 

Foreign  Seed  and  Riant   Introduction,  David  Fairchild,  Agricultural   Explorer  in  Charge. 

Forage  Crop  Investigations,  Charles  V.  Piper,  Agrostologist  in  Charge. 

Seed  Laboratory,  Edgar  Brown,  Botanist  in  Charge. 

Grain   Standardization,  John  D.  Shanahan,  Crop  Technologist  in  Charge. 

Subtropical  Laboratory  and  Garden,  Miami.  Fin..  Ernsl  A.  Bessey,  Pathologist  in  Charge 

Plant  Introduction  Garden,  Chico,  Cat.,  August  Mayer,  Expert  in  Charge. 

South   Texas  Garden,  Brownsville,  Tex.,  Edward  C.  Green,  Pomologist  in  Charge. 

Formeis'  Cooperative  Demonstration    11  ork,  Seaman   A.    Knapp,   Special  Agent    in   Charge. 

Seed  Distribution  (Directed  by  chief  of  Bureau),  Lisle  Morrison,  Assistant  in  General 
Charge. 


Fditov,  .1.  E.  Rockwell. 
Chief  Clerk,  James   E.   Jones. 


I  ONTENTS. 


Page. 

Introduction 5 

Procedure  in  experiments 6 

Powders  used 6 

Sulphur 6 

Dry  Bordeaux  mixture 6 

Coppei  sulphate  and  lime 6 

Sol  lit  inns  u-eil 7 

Potassium  sulphid  and  permanganate 7 

Formalin 7 

Sulphuric  acid 7 

3 


_ 


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B.  P.  I.—  304. 


THE  TREATMENT  OF  DAMPING-OFF  IX 
CONIFEROUS  SEEDLINGS. 


INTRODUCTION. 

Experiments  have  been  carried  on  by  the  writer  for  several  years 
in  testing  the  effect  of  various  chemicals  upon  the  damping-off  elis- 
or1 tender  coniferous  seedlings.  These  troubles  are  great  obsta- 
cles to  the  successful  production  of  such  seedlings  in  large  num- 
bers for  use  in  replanting  waste  or  unoccupied  land.  They  are 
caused  by  a  number  of  different  fungi  which  arc  being  studied  and 
will  short ly  be  described. 

The  results  of  the  first  experiments,  which  were  carried  on  entirely 
in  the  greenhouse,  were  taken  as  indication.-  of  what  might  be 
expected  in  actual  nursery  practice.  It  was  felt,  however,  that  the 
work  should  be  extended  to  Geld  conditions,  and  upon  testing  the 
preliminary  results  there  it  was  found  that  they  could  be  taken  only 
as  very  meager  and  insufficient  indications  of  the  results  to  be 
obtained  in  the  field. 

During  the  season  of  L907,  field  experiments  were  conducted  in 
several  nurseries  of  the  New  York  Forest,  Fish,  and  (lame  Commis- 
sion i  (me  of  which  is  operated  in  cooperation  with  the  Forest  Service 
of  the  United  States  Department  of  Agriculture)  and  of  the  Ver 
mont  State  Forestry  Commission,  located,  respectively,  at  Saranac 
Inn.  X.  V..  and  Burlington,  Yt.  These  experiment-  yielded  very 
interesting  results,  but  because  of  their  preliminary  nature  it  is  felt 
that  without  further  \  cry  rigid  tests  along  similar  lines  they  can  not 
be  accepted  as  furnishing  conclusive  proof  of  the  comparative  value 
of  t  he  chemicals  u-vd. 

The  great  interest  centering  about  these  diseases,  however,  makes 
of  value  every  scrap  of  practical  information  concerning  method-  of 
prevention.  Until  conclush'e  results  are  obtained  the  present  one- 
may  therefore  prove  useful  to  nurserymen,  but  they  should  be 
a.c, •pied  with  the  distincl  understanding  that  they  are  preliminary 
and  are  subject  to  later  modification. 

5 


6  TREATMENT    OF    DAMPING-OFF    IN    CONIFEROUS    SEEDLINGS. 

The  tests  here  outlined  are  being  continued  on  a  more  extensive 
scale,  and  it  is  hoped  that  the  present  season's  work  will  give  such 
results  that  there  can  be  no  doubt  as  to  the  conclusions  to  be  drawn 
from  them. 

PROCEDURE   IN    EXPERIMENTS. 

The  plots  used  were  located  in  seed  beds  12  feet  long  and  4  feet 
wide,  each  bed  being  divided  into  three  equal  parts  I  feet  square. 
The  chemicals  were  used  in  fine  powders  or  in  solutions,  according 
to  their  original  form  and  nature.  The  solutions  were  applied  with 
an  ordinary  sprinkling  can,  while  the  powders  were  sifted  on  the 
beds  with  a  very  simple  form  of  duster  having  a  perforated  bottom, 
through  which  the  powder  was  shaken.  The  solutions  were  applied 
to  the  soil  before  the  seeds  were  sown,  and  then  again  about  five  days 
after  the  seedlings  had  come  up.  The  powders  were  applied  to  the 
beds  only  after  the  seedlings  had  been  up  for  three  or  four  days. 
They  were  applied  in  very  light  coatings,  which  were  renewed 
promptly  after  each  rain.  This  renewal  is  not  necessary  except  for 
a  period  of  about  twTo  weeks,  beginning  three  or  four  days  after  ger- 
mination, when  the  seedlings  are  most  susceptible  to  the  attacks  of 
the  damping-off  fungi. 

POWDERS  USED. 

Sulphur. — Sulphur  was  obtained  in  three  forms:  Washed,  resub- 
limed,  and  precipitated.  Favorable  results  were  given  by  all,  but 
the  first  led  the  others  slightly.  It  was  noted,  too,  that  a  distinct 
odor  of  sulphur  could  be  detected  at  least  8  inches  above  the  surface 
of  the  plot  treated  with  washed  sulphur,  while  no  perceptible  odor 
could  be  detected  over  the  other  two  at  a  greater  distance  above  the 
surface  than  1  or  2  inches.  This  difference  was  as  marked  several 
days  after  the  sulphur  had  been  applied  as  it  was  immediately  after 
the  application  was  made. 

Dry  Bordeaux  mixture. — Dry  Bordeaux  mixture  made  according 
to  Scott's  formula"  was  also  tried,  but  the  method  of  preparation 
is  too  tedious  and  time  consuming  to  be  of  use  in  the  case  of  a  disease 
like  damping-off  unless  the  mixture  is  made  up  some  time  in  advance. 
It  is  seldom  practicable  for  the  nurseryman  to  give  the  necessary 
time  for  its  preparation,  owing  to  the  pressure  of  other  duties  at  this 
period  of  the  year.  This  powder  was  accordingly  discarded  for  a 
copper  sulphate  and  lime  mixture  which  is  easily  and  quickly  made 
up  as  required  and  apparently  should  give  as  good  results  as  the  Bor- 
deaux preparation. 

Coffer  sulphate  and  lime. — Powdered  sulphate  of  copper  was 
mixed  with  powdered  lime,  at  the  rate  of  1  pound  of  the  former  to 

°  Waite,  M.  P..  Fungicides.  U.  S.  Department  of  Agriculture,  Farmers'  Bul- 
letin 24.'',,  pp.  11-12,  1906. 


I  |;i   \  i  .MIX  I     OF    DAMPING-OF]      IN    CONIFEROUS   SEEDLINGS.  i 

in  pounds  of  the  latter,  in  the  following  way:  Fresh  stone  lime  was 
slaked  with  a-  little  water  a-  would  keep  the  slaking  in  progress. 
In  this  way  slaked  lime  was  obtained  in  the  form  of  a  line  powder. 
This  was  screened  and  very  thoroughly  mixed  with  the  powdered 
copper  sulphate,  and  was  then  ready  to  be  used.  Attention  i-  called 
to  the  need  of  thoroughly  mixing  the  two  ingredients,  a-  disastrous 
results  air  likely  to  ensue  if  the  coppei  sulphate  is  not  properly 
diluted  with  the  lime. 

This  mixture  was  used  very  freely  after  the  seedlings  had  come  up. 
Absolutely  no  injurious  results  could  be  noted,  even  when  the  applica- 
tions were  made  early  in  the  morning  while  the  seedlings  were  still 
wet  with  dew  mi  that  the  powder  stuck  to  them.  It  may  lie  said  that 
the  better  time  to  apply  the  powders  and  also  the  solutions  is  late  in 
the  afternoon.  The  powder-  will  then  adhere  very  slightly  to  the 
plant  let-  and  practically  all  of  the  powder  will  fall  on  the  soil,  where 
it    i-   wanted. 

This  copper  and  lime  mixture  was  used  upon  the  following  species: 
Pinus  sylvestris,  /'.  ponderosa,  /'.  strobus,  /'.  sinosa,  Picea  rubens, 
!'.  .  and  Pseudotsuga  taxifolia.     Very  good  results  were  ob- 

tained in  checking  the  damping-off  with  it.  and  it  is  believed  to  be 
one  of  the  mixture-  tested  which  may  prove  of  value  commercially. 

SOLI    nONS    I  -ll>. 

Potassium   sulphid  and  permanganate.     A  solution  of  potassium 

Sulphid,  made  :.!  the  rate  of  1  ounce  id'  dry  chemical  to  1  gallon  of 
water  and  applied  to  the  -oil  before  sowing  the  seed,  gave  no  definite 
results  because  of  the  absence  of  the  disease  in  the  experimental  plot-. 
This  was  also  true  of  a  -oh  it  ion  of  potassium  permanganate,  mixed  at 
the  rate  of  1  gram  of  chemical  to  1  gallon  of  water  and  similarly 
applied. 

Formalin.  -Commercial  10  percent  formalin,  used  at  the  rate  of  1 
ounce-  to  :;  gallons  of  water,  when  applied  to  the  -oil  before  seeding 
and  not  afterward  repeated,  seemed  to  have  no  effect  whatever  upon 
the  disease.  Tin'  check  plot,  indeed,  was  much  better,  a-  were  all  of 
the  other  plot-,  both  treated  and  untreated,  located  in  that  section  of 
the  nursery.  When  applied  a-  stated  and  repeated  after  the  seedlings 
had  come  up.  the  results  were  poor.  It  is  now  believed  that  formalin 
i-  of  little  value  with  the  damping-off  diseases  of  coniferous  seedlings 
unless  supplemented  after  the  germination  of  the  seed  with  some  other 
efficienl  chemical.  The  results  were  disappointing  when  compared 
with  those  obtained  w  ith  some  of  the  other  chemicals. 

Sul phuric  acid.  The  best  result-  were  obtained  with  weak  solution- 
id'  sulphuric  acid.  A  solution  mixed  at  the  rale  of  1  ounce  of  acid  to 
1  gallon  id'  water  was  applied  t,»  the  -oil  several  days  before  sowing 


8  TREATMENT    OF    DAMPING-OFF    IN    CONIFEROUS    SEEDLINGS. 

the  seed,  until  it  was  thoroughly  drenched,  and  the  treatment  was  re- 
peated about  a  week  after  the  seedlings  came  up.  The  treated  plot 
was  in  excellent  condition  in  December:  there  was  a  very  good  stand 
of  fine,  healthy  seedlings  and  the  soil  was  entirely  free  from  algae  and 
moss.  The  check  plot,  on  the  other  hand,  had  practically  no  seedlings 
left,  and  the  soil  was  green  with  algae  and  moss. 

This  solution  of  sulphuric  acid  was  applied  to  young  seedlings  of  a 
number  of  different  species,  and  but  one  showed  any  ill  effects.  This 
was  Norway  spruce  (Picea  excelsa).  It  is  not  advisable  to  use  an 
acid  solution  as  strong  as  this  upon  the  plants.  Kraemer «  has  shown 
that  a  solution  of  sulphuric  acid  at  the  rate  of  1  to  500  is  as  strong  as 
should  generally  be  used  upon  plant  tissues,  and  this  is  recommended 
rather  than  the  much  stronger  one  used  in  these  experiments  For 
soil  treatment  the  stronger  solution  will  probably  prove  preferable. 

Approved : 

James  Wilson, 

Secretary  of  Agriculture. 

Washington,  D.  C.  April  6\  1908.  


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"Kraemer,    Henry     Dilute    Sulphuric-    Acid    as    a    Fungicide.     Proceedings. 
American  Philosophical  Society,  vol.  45,  pp.  157-163,  1906. 


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